塔里木荒漠河岸林植物群落演替下的土壤理化性质研究

选择塔里木荒漠河岸林内典型、有代表性的不同演替阶段的群落,对其土壤理化性质进行研究。结果表明：土壤理化性质在演替方向和土壤剖面上表现出较强的规律性。演替后、中期表层土壤（0～20 cm）粘粒质量分数比初期分别减少了1.28%、64.29%、土壤砂粒质量分数分别增加了3.08%、17.23%,土壤明显变粗沙化。群落演替能明显增大土壤容重与非毛管孔隙度,降低土壤总孔隙度、毛管孔隙度、孔隙比、土壤水分质量分数、最大持水量、毛管持水量和最小持水量。演替后、中期表层土壤非毛管孔隙度比初期分别增大了33.78%、36.087%,土壤水分质量分数分别降低了85.57%、97.77%,演替后期最大持水量、毛管持水量分别比初期降低了40.28%、9.27%,导致土壤固相率减小,气相率增大,土壤持水供水能力与抗风蚀性能减弱。土壤有机质、全氮与碱解氮、全磷与速效磷、全钾与速效钾、盐分质量分数随群落演替呈降低趋势。演替后期表层土壤有机质、碱解氮、全磷与速效钾质量分数分别比初期降低了38.68%、60.71%、23.58%、66.93%,其土壤理化性质退化最显著。地下水位下降是引起荒漠河岸林植物群落逆向演替的驱动力。当前随人类干扰强度增强（水土资源开发）,塔里木荒漠河岸林土壤结构与土壤生态功能随之受到破坏与衰退,而保持合理的生态水位则是维持荒漠河岸林生态系统稳定的有效途径。

Soil physical and chemical properties under succession of plant community in desert riparian forest of the Tarim River

Typical and representative plant communities in different succession stages were selected to study the effect of succession stages on the soil physical and chemical characteristics in the Tarim＇s River riparian forests.The results showed that obvious variations in soil properties existed in different succession stages.Clay contents in the 0~20 cm layer of the mid and later succession stages decreased 1.28% and 64.29% than that of the early stage,respectively,while contents of sand particle of these two stages increased 3.08% and 17.23%,respectively.The soils exhibited the tendency of increasing soil particle size and getting sand.Furthermore,soil porosity,capillary porosity,soil water content,maximum water holding capacity,capillary water holding capacity and minimum water holding capacity all decreased obviously,soil bulk density and noncapillary porosity increased distinctly as succession went on.Solid phase ratios decreased and air phase ratios increased,the capacity of water-holding and water-supplying,the wind erosion resistance reduced.Surface soil noncapillary porosity of the mid and later stages increased 33.78% and 36.08% than that of the early stage,soil water content of these two stages decreased 85.57% and 97.77%,respectively.Surface soil（0~20 cm） maximum water holding capacity and capillary water holding capacity of the later succession stage decreased 40.28% and 9.27% than those of the early stage,respectively.The contents of soil organic matter,total N,P,K,and available N,P and K decreased distinctly,but no obvious variation was observed for soil pH value.The content of surface soil organic matter,total P and available N,K of the later succession stage decreased 38.68%,60.71%,23.58% and 66.93% than that of the early stage,respectively.The soil fertility gradually decreased with increase of soil depth in different succession stages,the soil physical and chemical property of the later succession stage decreased distinctly.Decline of groundwater level is the driving force to lead converse succession of plant community ofdesert riparian forest in Tarim basin.Currently,the soil structure and ecological function of desert riparian forest were destroyed and degraded with increasing of antrhropogenic disturbance intensity in the Tarim basin,but keeping the rational ecological groundwater level is the effective path to sustain desert ecosystem stability.